Lighting system.



W. I. THOMSON.

LIGHTING SYSTEM.

APPLICATION FILED APR.15, 1903.

926,51 8. Patented June 29, 1909.

I B) W A TTORNE S WILLIAM I. THOMSON, OF NEWARK, NEW

JERSEY, ASSIGNOH TO SAFETY CAR HEATING (S's LIGHTING COMPANY, A CORPORATION OF NEW JERSEY.

LIGHTING SYSTEM.

Specification of Letters Patent.

Application filed April 15, 1903.

Patented June 29, 1909.

Serial No. 152,648.

lng Systems, of which the following is a full,

clear, and exact description, such as will .enable others skilled in the art to which it appertains to make and use the same.

The invention relates to a system especially adapted for what is known as car axle lighting wherein the electricity which supp ies the lamps is generated by a dynamo mounted upon or driven from the car axle. It is, however, capable of use in a variety of relations.

One of the objects thereof is to rovide a means whereby the output of the ynamo is self-regulatable or controlled in accordance with the speed of the train.

Other objects and advantages will appear hereinafter.

The invention accordingly consists in the features of construction, combinations of elements, arrangement of arts and inter-relations of the system, w ich will be hereinafter more'fully described and the novel features thereof pointed out in the claims.

In the accompanying drawings, Figure 1 illustrates diagrammatically a system embodying the invention. Fig. 2 is a detail showing a modification of certain of the elements of the system shown in Fig. 1.

Similar reference characters referto similar parts throughout the several views.

The lamps'and storage battery of a car lighting system are indicated at 1 and 2 respectively as embodied in the main circuit of a dynamo 3 which is preferably driven, either directly or indirectly, from a car axle. The leads of this main circuit are represented at 4, 5, 6 and 7, a switch being interposed at 8 and the coils of a solenoid 9 being interposed between the leads 6 and 7.

, The function of switch 8 is, as will be obvious from the drawings, to open the circuit throu h the dynamo 3 and prevent any wasteful discharge of battery 2. The coils of the field magnet or magnets of the dynamo are represented at 10 as shunt-wound, the leads of the shunt circuit being indicated at 11 and 12. Embodied in this shunt field circuit is a variable resistance which is illustrated as comprising a pile or series of carbon disks or other contacting electrodes 13 located between the plates 14 and 15 to which the leads 11 and 12 are connected. The lower of these plates is stationary and the upper one is carried by an insulated arm 16 pivotally connected to the end of the lever 17 pivotally mounted at 18. To the other end of this lever is ivotally connected the plunger 19 of the so enoid 9. A retractile spring 20 tends to rock the lever 17 on its pivot so as to increase the pressure of the plate 14 on the pile of carbon disks, thereby lessening the resistance of such pile and the resistance of the field circuit of the dynamo. There is also preferably provided a means for absorbing any sudden movements or jerks of-the lever 17, as a dash-pot 20 having its iston 21 connected to one of the arms of the ever.

The operation and advantages of such a system will be apparent to those acquainted with the art, but they may be briefly summarized. The dynamo gives its normal output at a certain train speed. The parts should be so adjusted that as the speed increases the increased current in the main circuit causes the plunger of the solenoid to be drawn down, thus diminishing the pressure on the pile of carbon disks and increasing the resistance of the field of the dynamo. The variations of resistance of the pile of carbon disks due to slight variations in pressure are so great that a very slight movement of the solenoid will be sufficient to react strongly upon the dynamo and to compensate for the increase in speed. At low train speeds the carbons will be pressed tightly together by the action of the rctractile spring, thus enabling the dynamo to build up rapidly.

It will be apparent that this system provides means whereby a source of energy adapted to supply a current for any desired use may be caused to react upon itself in order to regulate the amount of energy supplied, thereby tending always to bring the output of such energy to normal. The advantages of such a seIf-regulatable system, both general and s ecific, will be clear without elaboration. ertain advantages to be noted, however, reside in the fact that with the proposed system I am enabled to regulate satisfactorily the output of a shunt wound dynamo, with a field produced by a single circuit only, thereby doing away with the com licated wiring of other systems, wherein t e field is a compound one embodying differential series coils and the like. This solenoid is introduced in the main circuit, so

facility of regulation is due, among otherl things to the peculiar advantages of the variable resistance device which I use and to the fact that the shunt circuit inwhich said resistance is introduced is taken ofl from the main circuit, as shown; at points nearer to the dynamo than the point at which the that the field circuit may besaid to be independent of the controlling device in the main circuit.

It will be obvious that theinvention is not limited to the details shown in the present embodiment, as various changes may be made in the system illustrated Without dearting from the scope of the invention.

or example, there may be substituted for the carbon disks carbon in granulated or other form, or other material whose resistance changes with pressure.

Fig. 2 shows a modified arrangement of the carbon disks, wherein such disks are in two piles with one of the leads of the field circuit of the dynamo connected to each of the piles, the two piles being connected by a conducting arm 22, which conducting arm is carried from the end of the lever 17. By this arrangement, a given motion of the solenoid plunger will produce a greater change in the resistance of the field circuit and a more sensitive and quickly responsive action is obtained.

Having described my invention, what I claim as new and desire to secure by Letters Patent is:

' 1. In combination, a shunt wound generator having serially included in its field circuit a plurality of contacting electrodes and positively acting electromagnetic means controlled by the current output of the generator for varying the pressure with which said electrodes contact.

2. In a car axle li hting system, in combination, a dynamo adapted to be driven from a car axle, said dynamo having a single field circuit shunt wound from the main circuit, a

variable resistance device included in said field circuit, said device embodying a material whose resistance varies withpressure, a controlling device in series with the main circuit of the dynamo, said controlling device adapted to be operated by variations of current in said main circuit, and connections from said controlling device for varying the pressure on said resistance device.

3. In a car axle li hting system, in combination, a dynamo ac apted to be driven from a car axle, said dynamo having a field circuit shunt wound from the main circuit, a series of carbon disks interposed in said field circuit, a controlling device adapted to be actuated by variations in current in the main circuit of the dynamo and in series therewith, a connection between said controlling device and said disks such that pressure on said disks is decreased as the current in the main circuit increases, and a spring acting upon said disks in opposition to said controlling device to increase the pressure thereon.

4. In a'car axleli hting system, in combination, a dynamo a apted to be driven from a car axle, saiddynamo having a field circuit shunt wound from the main circuit, a series of carbon disks included in said field circuit, a solenoid in series with the main circuit of the dynamo and independent of the field circuit, a connection between the plunger of said solenoid and said disks such that the pressure upon said disks is decreased as the current in the main circuit increases, and a spring adapted to act upon said disks to increase the pressure thereon in opposition to said solenoid.

In testimony whereof I aflix my signature, in the presence of two witnesses.

WILLIAM I. THOMSON.

l/Vitnesses F.- E. KESSINGER, T. P. WARFIELD. 

